James Rahon scored 30 or more points seven times as a senior at Torrey Pines High, and 41 once. He broke the freshman record for 3-pointers in a season at Santa Clara. He made 43.7 percent of his 3s as a sophomore at San Diego State, and scored in double-figures 13 times as a junior.

As a senior, he ranks third in the nation in fewest turnovers per minute.

But the reason SDSU coach Steve Fisher’s mood brightened Monday afternoon when he saw Rahon practicing for first time since spraining his right shoulder nine days earlier had little to do with his offensive reputation.

It has to do with one of the best-kept secrets in the Mountain West: The 6-foot-5 senior guard has quietly become one of its best perimeter defenders.

It also has with the Aztecs’ opponent Wednesday night: New Mexico.

The No. 14 Lobos (23-4, 10-2) are coming off their biggest win of the season, 91-82 at Colorado State to give them sole possession of first place, and that was in large part due to a career-high 46 points from guard Kendall Williams, and Rahon’s usually draws Williams on defense. In their last meeting, SDSU’s 55-34 defensive clinic at Viejas Arena on Jan. 26, Williams made one 3-pointer and finished with 14 points; he drained 10 beyond the arc against Colorado State and scored 18 points alone over the final six minutes.

“James has become our best defender chasing guys off screens,” Fisher said. “He never gets tired. He fights through screens and doesn’t get stood up, doesn’t get taken out by screens. He’s relentless. And he has size to go with it. He has a little length about him.

He’s by far our best defender in that regard.”

Or just look at what happens when he doesn’t play. Nevada guard Malik Story made seven treys and had 33 points Saturday – the most against an SDSU team in 61 games – with Rahon sidelined.

“I think,” Fisher said, “he would have run Story off a couple of those screens.”

It was the one screen Rahon couldn’t avoid, from 6-foot-8, 240-pound UNLV freshman Anthony Bennett on the game’s first possession, that got him hurt two Saturdays ago. Rahon hadn’t practiced or played since.

“I didn’t know it was coming,” Rahon said. “It was Bennett, and that’s not a good person to hit. It felt like I hit a brick wall.”

Rahon didn’t participate in the entire SDSU practice Monday, but he was able to raise his arm high enough to shoot and he did step into a few full-contract drills against the scout team. He said Wednesday still figures to be a “game-time decision,” but he admitting being “pretty encouraged with how much I did today.”

He credits two things for his transformation from a guy who can shoot it to someone who stops guys who can shoot it: added strength “to dictate where they’re going to go,” and insider knowledge.

“I think just playing for four years, you kind of get to know what players do out there,” Rahon said. “I’m used to coming off a lot of screens, so guarding someone, I kind of have a feel for what they’re going to do.”